Excessive Oil Consumption

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Submissions by Jacks (R.I.P.)

Excessive Oil Consumption:

Some of the possible causes for this are
1: Oil Leaks
2: Worn or broken rings
3: Excessive clearance, in the valve stems guides
4: Damaged or worn valve stem oil seals,
5: The rings being to tight and stuck in the grove
6: Excessive wear in cylinders, piston and rings
7: Compression rings incorrectly installed
8: Oil ring broken or clogged up
10:Wrong Rocker Covers. After Market Rocker Covers have small baffles that allow oil into the PCV system
If the valve don't stay up, with the compressed air then the valves are leaking, so attention to these may be required, however if you still want to carry on you can put some tape around the end of the stem, that should allow you to carry on for the fit the valve stem oil seals

Damaged or worn valve stem oil seals:

This is in relation to a question on how to remove/replace the valve stem “oil seal��? and not drop the valve down the cylinder

Starting Position:

Remove the spark plugs and the dizzy cap, remove the rocker cover, next rotates the crankshaft by hand, so the No 1 cylinder is up at the top of the stroke, check to confirm the tappet rockers as they should now have "zero" clearance between the valve stem and the rocker, you also can make up or buy an adaptor that can be screwed into the spark plug hole ,which will allow you to put compressed air into the cylinder chamber forcing the valve closed.
Best to do one cylinder at a time, if you remove all the rockers in one go you may get confused as to the whereabouts of the piston in the cylinder, as the position is in relation to the rocker's, so if they are all removed at once then they will all be level and then your lost, hope you get my drift
So only remove the rockers etc once you have got TDC of the cylinder your working on
Important: note were the rockers, push rods etc came from as they need to go back in the original position
The DIY tool placed in a position using the arm bolt to hold the compressor tool so you can get leverage to press downward on the valve cap, make sure the cut out section on the end of the tool will fit over the valve cap, (see picture )and that it will also allow you to access the two cotters that are held firmly in place by the valve cap.
Click to enlarge DIY Valve Compressor Tool

when pressure is applied downwards on the valve spring assemble you should then be able to remove the two cotters held firmly in the two grooves of the valve stem
Some times these little suckers can be a bit slippery and can easily be dropped, so hold them firmly be careful when removing, don’t drop them down the oil cavities that the push rods go into, if you do, then you will need to remove the side plate and retrieve them
However the best bet is to cover the holes with a cloth before you start, also have a pair of long nose pliers handy, or a small magnet rod for the cotters to stick onto

Oil Seal:

With the two cotters now removed as well as the valve spring cap, this should now reveal the valve stem “ oil seal? it looks like a small “O? ring? situated just below the two cotter groves in the valve stem
Also situated there is the shroud that sits on the top of the valve spring.
If the oil seal is missing, then you can sometimes see them laying at the bottom of the valve spring.

Failed Oil Seal:

The reason it splits open ,swells up, or breaks and fails, is that the oil seal will become somewhat saturated with oil and heat causing fatigue, then for it to fail, enlarging, or spilt open,

Smoking Exhaust:

When this happens, the oil will then run down the valve stem guides, into the combustion chamber and burn, hence the reason for smoke to be detected from the exhaust,
This is more prevalent once the engine as been stationary for a while as the oil on the valve stems get a longer period to weep down into the valve guides,
As there is more oil now been accumulated in the cylinder chambers so that now when you start up the engine there is more oil to burn , hence a bigger puff of oil from the exhaust,
That’s the first clues of oil getting down the valve guides, as there’s only three ways this can happen ,either worn valve guides, broken oil seal or worn out oil seals,

Pressure build up:

So if the valve guides are worn some what, you will get more pressure built up inside the Rocker cover case, due to the fact that the pressure from the exhaust stroke, well some of it, will go up the worn valve guides, the same can be said for the inlet valves guide as well
one way of seeing that is by removing the oil filler cap on the Rocker cover with the engine running, there you can see an oily smoke telltale story coming out of the filler hole, as the compression from the cylinders force there way up the valve stem guides, making a mess
However, if it’s the Piston Rings that are worn out, then that’s another story, as a WET Compression Test should re-veil that for you , or maybe a Leak Down Test

Positive Crankcase Ventilation:

Its important to maintain good ventilation for you engine, as the PVC valve is controlled by the engine RPM, the plunger and spring are the only two moving parts inside the valve chamber so it’s they be checked at regular intervals, make sure that the hose connection are secure no cracks as the loss of vacuum will effect the efficiency of the PCV valve and a pressure will build up inside the crankcase as well as the rocker cover.After market rocker covers can be a major cause of oil burning check the PCV page.

Testing Ventilation Valve:

If you have a tachometer, then set the motor at a smooth idle speed, take note of what the engine RPM is, next remove the hose from the ventilation valve, block up the hose with a suitable plug so its not sucking air, now check your tachometer, if the RPM has dropped by 50 RPM or more, then the crankcase ventilation system OK.
However if the RPM drops Less than 50 RPM, then I’d say it’s properly partially blocked, may even be fully clogged up,
So it will need to be pulled apart and cleaned properly, a simple process, if it looks faulty ,then buy a new one
Don’t forget to recheck it again, as the hose could be blocked as well, also the check the end of the hoses make sure there not sucking in air